In a liquid chromatograph mass spectrometer, a liquid chromatograph is connected to a mass spectrometer through an interface (for example, refer to Patent Document 1). FIG. 5 shows a schematic configuration of a common liquid chromatograph mass spectrometer. The interface consists of an ionization probe 2 and a sample introduction unit 3. The mass spectrometer consists of a vacuum chamber B and a mass analyzer 4. A sample introduced from a liquid chromatograph 1 is sprayed from the ionization probe 2 and ionized inside an ionization chamber A under atmospheric pressure. The ionized sample is introduced to the mass spectrometer through the sample introduction unit 3 connecting a first separation wall 13 and a second separation wall 14 disposed between the ionization chamber A under atmospheric pressure and the vacuum chamber B. The spray direction of the ionization prove 2 and the direction of introducing the sample to the sample introduction unit 3 are arranged to be perpendicular to each other. The sample introduction unit 3 is heated to remove noise components or solvent components.
The following description will discuss a configuration of the conventional sample introduction unit 3 with reference to FIG. 4. FIG. 4(b) is a cross-sectional view illustrating a structure of the sample introduction unit, and FIG. 4(a) is a left side view of FIG. 4(b). As shown in those figures, the sample introduction unit 3 consists of a pipe 5, a first electrode (holding member) 6, a second electrode (holding member) 7, a resin collar 8, a temperature detector 9, a ferrule 10, a push screw 11, a plate 12, a first setscrew 17, a second setscrew 18, a first support 15, and a second support 16.
The first electrode 6, the second electrode 7, the ferrule 10, the push screw 11, the first support 15, and the second support 16 among the previously listed members are all made of conductive materials, such as stainless steel.
In the sample introduction unit 3, the pipe 5, and the first electrode 6 and the second electrode 7 which are connected to the pipe 5 are collectively called a pipe section. The pipe section is detachably attached to the mass spectrometer, details of which will be explained later.
The pipe 5 is made of a conductive material such as stainless steel, and the ionized sample is introduced from the ionization chamber A to the vacuum chamber B through the pipe 5.
The pipe 5 and the first electrode 6 are fixed to each other with the plate 12 at a vicinity of the front end of the pipe 5 (on the side of the ionization chamber A). The pipe 5 and the second electrode 7 are fixed to each other with the ferrule 10 and the push screw 11 at a vicinity of the back end of the pipe 5 (on the side of the vacuum chamber B). The first electrode 6 is insulated from the second electrode 7 with the resin collar 8 interposed therebetween.
The first electrode 6 has an integrally-formed first electrode connector portion 6a which is perforated with a first fixation hole F. The first electrode connector portion 6a is connected, with the first setscrew 17, to a tip, specifically a first support connector portion 15a, of the first support 15 extending in parallel with the pipe 5 from the second separation wall 14.
The second electrode 7 has an integrally-formed second electrode connector portion 7a which is perforated with a second fixation hole G. The second electrode connector portion 7a is connected, with the second setscrew 18, to a tip, specifically a second support connector portion 16a, of the second support 16 extending in parallel with the pipe 5 from the second separation wall 14.
In this manner, the sample introduction unit 3 is connected to the first support 15 and to the second support 16 using the first setscrew 17 and the second setscrew 18, respectively. Accordingly, the sample introduction unit 3 is installed to the second separation wall 14.
The first support 15 and the second support 16 are both formed of a conductive material, such as stainless steel. The first support 15 is coupled to a first power cable crimp terminal 19 extending from a power source (not shown in the figures), and the second support 16 is coupled to a second power cable crimp terminal 20 extending from the same power source.
When a voltage is applied from the power source to the first power cable crimp terminal 19 and the second power cable crimp terminal 20, an electric current is supplied to the pipe 5 through the first electrode 6 and the second electrode 7 to heat the pipe 5. The temperature detector 9, including a platinum sensor and other devices, is mounted on the pipe 5. Based on the temperature detected by the temperature detector 9, the temperature of the pipe 5 can be appropriately controlled.
Electric insulation is maintained with a resin material member (not shown) between the first electrode 6 and the first separation wall 13, between the second electrode 7 and the second separation wall 14, between the first support 15 and the second separation wall 14, and between the second support 16 and the second separation wall 14.
[Patent Document 1] Japanese Unexamined Patent Application Publication No. 2003-202325